title: Eye movements in response to electrical stimulation of the lateral and superior ampullary nerves.
abstract: OBJECTIVE
  Recently, we demonstrated that it was possible to elicit vertical eye movements in response to electrical stimulation of the posterior ampullary nerve. In order to develop a vestibular implant, a second site of stimulation is required to encode the horizontal movements.
  
  
  METHODS
  Three patients with disabling Meniere's disease were included in the study. Before a labyrinthectomy via a standard transcanal approach was performed, their lateral and anterior ampullary nerves were surgically exposed under local anesthesia through a procedure we recently developed. The attic was opened, the incus and malleus head were removed, and a small well was drilled above the horizontal portion of the facial nerve canal to place an electrode. This electrode was used to deliver balanced biphasic trains of electrical pulses.
  
  
  RESULTS
  The electrical stimuli elicited mainly horizontal nystagmus without simultaneous stimulation of the facial nerve.
  
  
  CONCLUSIONS
  It is possible to stimulate electrically the lateral and superior ampullary nerves without simultaneous stimulation of the facial nerve. Because the nerves run close to each other, electrical stimulation provoked eye movements that were not purely horizontal, but also had some vertical components. Nevertheless, this site can be used to encode horizontal movements, because central adaptation may correct unnatural afferent vestibular cues delivered by a prosthetic sensor. The range of stimulus intensities that produced a response was broad enough for us to envision the possibility of encoding eye movements of various speeds.
authors.affiliation: Otorhinolaryngology-Head and Neck Surgery Service, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Switzerland.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Guyot
authors.forename: Alain
authors.initials: A
authors.lastname: Sigrist
authors.forename: Marco
authors.initials: M
authors.lastname: Pelizzone
authors.forename: Georg C
authors.initials: GC
authors.lastname: Feigl
authors.forename: Maria Izabel
authors.initials: MI
authors.lastname: Kos
mesh_terms: D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology; D008875:Middle Aged; D012665:Semicircular Canals / Q000294:innervation*